Turning spell check off permanently

Is there any way to turn off the spell checker so that it goes away? It annoys me to no end, since I use many non-English names and words and inevitably every other word is underlined in red dots as I go. I have it turned off in my browser settings so I'm pretty sure it's the WordPress spell check that is irritating me.

If it is Firefox's spell checker, you can right-click (or the mac equivalent) and add words to the dictionary (useful, if you have repeated names). In Firefox 2, at least, there's an option for "check my spelling as you type" in the advanced options, if it gets too annoying.

I've now upgraded (finally), and unchecking that does seem to turn off spell-checking, but only after you reload the current page or go to another one. I'm on Windows XP, which might make a difference.